Flotation process involving depression of sulfide minerals previously activated



United States Patent FLOTATION PROCESS INVOLVING DEPRESSION F SULFIDE MINERALS PREVIOUSLY ACTI- VATED Howard D. Cox, Las Vegas, Nev., assignor to Kennecott Copper Corporation, New York, N.Y., a corporation of New York No Drawing. Filed Apr. 17, 1964, Ser. No. 360,775

6 Claims. (Cl. 209-167) This invention relates to processes of differential flotation applicable to metallurgical pulps containing at least one mineral sulfide.

In particular, the invention is concerned with flotation processes of this general type which involve the depression of at least one mineral sulfide that has been previously activated and would normally float when the metallurgical pulp is subjected to a usual collection flotation procedure.

In the treatment of copper sulfide ores containing minor quantities of molybdenite (molybdenum disulfide), the molybdenite ordinarily accompanies the copper sulfides in the metallurgical concentrates obtained by the flotation treatment of the raw ores. It is then necessary to separate such molybdenite from the copper sulfides and from any other sulfides-notably iron sulfide-in the metallurgical concentrates thus obtained.

Various special flotation processes have been developed in the past for this purpose. Some of these have involved the selective depression of molybdenite, others the depression of the other sulfides and flotation of the molybdenite. In actual commercial practice, it has been found advantageous to utilize both types in order to obtain a satisfactory molybdenite concentrate.

Thus, it has long been accepted practice to effect an initial separation between copper and iron sulfides, on the one hand, and molybdenite on the other, by floating off the former while depressing the latter in some suitable manner, and to then subject the molybdenite concentrate (sink product) so obtained to a relatively expensive heating procedure, whereby surface characteristics of the remaining copper sulfides are altered to prevent them from floating when the concentrate is subjected to a re-flotation procedure with a collector reagent for the molyb denite.

Although special flotation processes have been developed which purportedly eliminate the need for heating the molybdenite concentrate to effect cleaning thereof upon the application of -re-flotation procedures, for one reason or another none have gone into extensive commercial use.

A principal object in the making of the present invention was to provide an effective and economical flotation process for separating molybdenite from copper and iron sulfides in metallurgical concentrates containing them all, by which usual heating procedures become unnecessary.

This object was accomplished by the use of a known compound, disodium aceto dithio carbonate (NaS COCH CO Na) as a depressant flotation reagent for sulfide minerals other than molybdenite. The compound is a Xanthogenat-ion product of hydroxy acetic acid.

Although I am primarily interested in the separation of molybdenite from copper and iron sulfides in metallurgical concentrates containing them all, the process of the invention has more general application. Thus, it may be applied to the re-flotation of any sulfide metallurgical pulp where depression of sulfide minerals other than molybdenite is found desirable, e.g., for the separation of such sulfide minerals from organic materials when the sulfide minerals have been previously activated by such collector reagents as Xanthates, thiophosphates, dithiocarbamates, and derivatives of these compounds.

The particular compound found to be especially suitable for my purpose, disodium aceto dithio carbonate, is only one of a group of compounds that can be employed in the process with more or less satisfactory results. Thus, compounds conforming to the type formula:

MXRCOOM or MXRCOOM where M represents any cation of a weak or strong base, e.g., hydrogen, sodium, potassium, ammonia, etc., X represents a compound corresponding to the activator reagent, e.g., a xanthate (S CO), thiophosphate (mono: SPO di: S PO; tri: S PS), dithiocarbamate (NCS and, derivatives thereof, and R represents an organic radical, e.g., alkyl, serve as depressants for sulfide minerals (other than molybdenite) which have previously been activated by such collector flotation reagents as a Xanthate, a thiophosphate, a dithiocarbamate, and derivative compounds.

Following are examples of laboratory and pilot plant work using disodium aceto dithio carbonate as a depressant reagent in connection with the re-flotation of a copper sulfide molybdenite concentrate derived by conventional flotation of a copper sulfide ore using butyl Xanthate as a collector reagent and pine oil as a frother reagent in a lime conditioned metallurgical pulp:

EXAMPLE I Rougher Flotation: Lbs. per ton Lime 4.5 Burner oil 0.36 Disodium aceto dithio carbonate 2.2

Cleaner Flotation No. 1:

Disodium aceto dithio carbonate 1.1

Cleaner Flotation No. 2: i 1 Sodium carbonate 0145 Sodium silicate n -1 0.45 Disodium aceto dithio carbonate 0.22

Regrind of No. 2 Cleaner Concentrate:

Disodium aceto dithio carbonate 0.22 Sodium silicate 0.45 Sodium carbonate 0.45 Pine oil 0.025 Zinc cyanide 0.45

Cleaner Flotation No. 3:

No reagent addition.

Metallurgical results Percent Product Weight Percent Distribu- Pereent MOS: tion Rougher Tailing. 92. 20 15 31. 45

No. 1 Cleaner Tailing 6.72 63 9. 59

No. 2 Cleaner Tailing 76 6. 87 11.90

No. 3 Cleaner Tailing .11 '19. 02 4. 77

Cleaner Concentrate 21 B8. 31 42. 29

Calculated Feed 100. 00 0. 44 100.00

Cleaner concentrate assayed 88.31%

3 EXAMPLE II This was a similar laboratory test, with reagents added as follows:

Rougher Flotation: Lbs. per ton Lime 4.4 Burner oil 0.35 Disodium aceto dithio carbonate 2.2

Cleaner Flotation No. 1:

Disodium aceto dithio carbonate 1.1

Cleaner Flotation No. 2:

No reagents. Cleaner Flotation No. 3:

No reagents.

Metallurgical results Percent Product Weight Percent Distribu- Percent MoSz tion MoSz Rougher Tailing 93. 42 051 23.14

No. 1 Cleaner Tailing 5. 68 .43 11.86

No. 2 Cleaner Tailing 65 4. 27 13. 42

No. 3 Cleaner Tailing... .19 28. 63 26.45

Cleaner Concentrate .06 *86. 21 25.13

Calculated Feed 100.00 .21 100.00

Cleaner concentrate assayed 86.21% MoSg, 1.21% Cu, 0.60% Fe, and 4.8% acid insoluble.

EXAMPLE III Following is a typical log of results from pilot plant work spanning a weeks operation, where no attempt was made to clean the resulting M08 concentrates to a marketable grade product:

Disodium aceto Percent MoSa dithio carbonate Percent (lb. per ton plant Recovery feed) Heading Tailing Concen- MOS:

trate Whereas there are here specifically set forth certain preferred procedures which are presently regarded as the best mode of carrying out the invention, it should be understood that various changes may be made and other 4 procedures adopted without departing from the inventive subject matter particularly pointed out and claimed herebelow.

I claim:

1. In a process of flotation for separating molybdenite from sulfides of metals other than molybdenum, which molybdenite and which sulfides have been previously activated for flotation from associated materials by means of a xanthate, the step of subjecting a flotation pulp containing said molybdenite and the other sulfides to froth flotation in the presence of a frothing and collecting agent for molybdenum and of disodium aceto dithio carbonate as a depressant reagent serving to depress the said sulfides of one or more metals other than molybdenum.

2. The flotation procedure of claim 1, wherein the sulfides of One or more metals other than molybdenum had previously been activated by contact with a reagent selected from the group consisting of a Xanthate, thiophosphate, and dithiocarbamate.

3. In a process of flotation applied to a mixture of sulfides of one or more metals, other than molybdenum, and one or more other materials susceptible of flotation, which sulfides have been previously activated by a Xanthate, the step of subjecting said mixture to froth flotation in the presence of a frothing and collecting agent for the said one or more other materials susceptible of flotation and of disodium aceto dithio carbonate as a depressant reagent serving to depress the said sulfides of one or more metals other than molybdenum.

4. The flotation procedure of claim 3, wherein the sulfides of one or more metals other than molybdenum had previously been activated by contact with a reagent selected from the group consisting of a xanthate, thiophosphate, and dithiocarbamate.

5. A process according to claim 1, wherein the molybdenite and the sulfides of one or more metals other than molybdenum have been previously activated by butyl Xanthate.

6. A process according to claim 3, wherein the sulfides have been previously activated by butyl Xanthate.

References Cited UNITED STATES PATENTS 1,593,232 7/1926 Whitworth 209-166 1,684,536 9/ 1928 Fischer 209-166 1,976,203 10/1934 Trotter 209167 X 2,070,634- 2/1937 Werntz 209-166 X 2,501,269 3/ 1950 Fischer 209166 2,811,255 10/1957 Nokes 209167 HARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner. 

1. IN A PROCESS OF FLOTATION FOR SEPARATING MOLYBDENITE FROM SULFIDES OF METALS OTHER THAN MOLYBDENUM, WHICH MOLYBDENITE AND WHICH SULFIDES HAVE BEEN PREVIOUSLY ACTIVATED FOR FLOTATION FROM ASSOCIATED MATERIALS BY MEANS OF A XANTHATE, THE STEP OF SUBJECTING A FLOTATION PULP CONTAINING SAID MOLYBDENITE AND THE OTHER SULFIDES TO FROTH FLOTATION IN THE PRESENCE OF A FROTHING AND COLLECTING AGENT FOR MOLYBDENUM AND A DISODIUM ACETO DITHIO CARBONATE AS A DEPRESSANT REAGENT SERVING TO DEPRESS THE SAID SULFIDES OF ONE OR MORE METALS OTHER THAN MOLYBDENUM. 